The completion of the human genome project - the reading of the
very DNA which programs the creation of each us including our brains
from a single fertilized cell - suggests - indeed tempts us to believe
that the answer to who and what we are lies in our genes. What I
shall propose here is that genes are only half the story. The discovery
of neural plasticity suggests genes play a different role in us
than in other animals. Human evolution specialized us to transmit
through culture what in other animals is transmitted through genes.
That extragenetic information - passed through symbols - works by
exploiting neural plasticity to modify - reprogram - earlier evolved
functions into new ones. The genome does not make the humanities
irrelevant to understanding ourselves but paradoxically even more
important.

Genes and their evolution I should stress are central. When we
look in the mirror, we see the products of genes - our face with
the rest of our bodies - is a wonderful creation of a gene orchestrated
dance of embryological development choreographed by natural selection.
But what of our brains? Though created by genes and natural selection,
is understand these enough to know what happens to create our thoughts,
minds, emotions, and sense of being very much alive? Is evolution
and genetics the single factor -- as with our bodies -- in making
us who we are? Or it is only a factor with there being more to tell?

Adaptation and neurological evolutionary
psychologies

Two quite different stories - adaptational and neurological -
are emerging as to how human evolution and our genes link to the
science of our minds. First, and presently, the most popular one
- adaptational evolutionary psychology - argues that our brains
are like the organs of body in that their functions - mental faculties
-- are the products of natural selection. When we look at our hearts
or other organs, what we see in effect are marvelous pieces of evolutionary
engineering. Evolution did not exactly design them - evolution lacks
intent. But we can read back from the utility of their design, that
certain advantages for their survival caused them to be selected.
Adaptational evolutionary psychology claims that the faculties of
our minds like the organs of our bodies are in this way "designed".
The human brain in this view is made up of a wide variety of cognitive
"gadgets" - complex mental adaptations - whose engineering was selected
during the Pleistocene - roughly one and half million years until
10,000 years ago.

Adaptation evolutionary psychology leaves little room for culture
or the humanities: the core essence of what makes us human, according
to it, lies instead in the evolution of complex mental adaptations
during the Pleistocene.

Neurological evolutionary psychology also claims that when we
look in the mirror we see the product of genes and evolution. But
it sees this evolution stretching far back prior to the Pleistocene
to the origins of early reptiles and even earlier - hence the title
of the book explaining this approach: Up from Dragons (McGraw-Hill,
2002, Skoyles, J. R. and Sagan, D). Neurological evolutionary psychology,
in contrast, to adaptational evolutionary psychology does not propose,
however, that human evolution carried on this adaptation a stage
further by creating the cognitive gadgets of our minds - at least
not directly. Instead it argues that human evolution initiated non-genetic
adaptation by opening this earlier evolution in the human brain
to be refashioned by the extragenetic transmission. Human evolution
created a brain specialized at creating itself through inherited
culture not inherited genes. Thus, in this view, the human brain,
rather than being full of evolved cognitive gadgets, as claimed
by the adaptationists, consists of the equivalent of cogs, screws,
and other components out of which culturally transmitted learning
can create such cognitive gadgets. Culture is not something that
happens on top of minds - it is a programmer that creates minds.

Neurological evolutionary psychology synthesizes neurology - the
discovery of neural plasticity - and cultural studies - the role
of symbols.

Neural plasticity

Neural plasticity - the flexibility of neurons to take on functions
for which they were not evolved - is one of the great discoveries
of recent neuroscience. It does not deny that evolution optimized
much of the brain to carry out particular functions: what it observes
is such optimization did not determine that cerebral and other brain
circuits should also be limited in function by such specialization
-- and so remain open if appropriated trained to do quite different
things.

We know this due to Louis Braille. In those born blind, the part
of the brain that natural selection has for nearly 200 million years
in mammals being fine tuning them to see takes on a radically different
function - that of reading Braille. Further evidence for neural
plasticity is that if visual inputs from the retina in ferret embryos
are redirected to the auditory or somatosensory cortex rather than
go to the visual cortex, the circuits in this normally nonvisual
part of the adult ferret brain develop sight. No adaptational evolutionary
psychologist predicted a brain that could do this. Braille, after
all, as a tactile skill that from an evolutionary viewpoint should
be done in the somatosensory areas specialized for feeling with
the fingertips not those evolved for vision. What neural plasticity
reveals is that the circuits that make up the brain, while they
might be fated, are not determined by evolution to do a particular
function. It is a discovery with profound implications for understanding
human evolution.

Steven Pinker, an adaptational evolutionary psychologist, has
recently argued (Blank slate, 2002) that neural plasticity is "metaphor"
if applied to those brain areas that process higher cognition. He
is wrong: it is due to neural plasticity in these areas that our
minds are robust against the effects of age, dementia, and small
brain injuries. Brain tumors can grow to the size of small plums
- in doing so they destroy brain tissue; however because their growth
is so slow, the functions in these areas migrate to circuits nearby
leaving an individual cognitively intact. Due to such evidence of
the existence of neural plasticity, our understanding of aging and
the process of dementia has shifted dramatically in recent years
-functional imaging of the brain shows that the aging or dementing
brain goes through a process of adaptation with new areas taking
over functions previously done elsewhere in the brain - this process
minimizes the impact of brain deterioration. Of course, this process
can only go on until the "reserve" that enables such compensation
is exhausted and the effects of brain deterioration can no longer
be masked. Nonetheless, it is evidence that neural circuits are
flexible throughout the brain including those most recently expanded
in our evolution.

Neural plasticity and human evolution

Neural plasticity tells us that neural circuits evolved for one
function can, if appropriately trained, do functions that no brain
was evolved to do - cerebral circuits for sight, for example, can
turn into cerebral circuits for Braille reading. Human evolution
specialized the human brain to take advantage of this neural plasticity.

· First, it freed itself of the constraint of having insufficient
neural circuits available to take on new nonevolved functions by
expanding the cerebral cortex three fold.

· Second, it expanded the part of the brain best able to
train novel functions upon the brain - the prefrontal cortex. The
prefrontal cortex is central to learning. Very briefly, what has
been found about the prefrontal cortex argues it has skills for
making arbitrary linkages between processes elsewhere by holding
together them - a skill needed to make the stand-in relationship
of symbols - in "working memory".

· Third, the brain developed a powerful means for communicating
skills - language. At present, it is not clear how far this involved
speech rather than gestures - some have argued speech is a secondary
development that followed the earlier development of vocal skills
for singing. The details here are uncertain - what is clear is that
humans evolved a specialization that enabled our species to communicate
learning efficiently between generations.

Symbolization and the "stand-in" extension
of old functions

Neural plasticity enabled a fundamental revision of the capabilities
of the brain by reprogramming the old functions carried out by neural
circuits to new ends by means of symbols. Basically, symbols make
one thing stand-in cognitively for another. An already evolved process
"X" that processes inputs "Y" can process - when rewired by neural
plasticity - inputs "Z". The inputs "Z" act as stand-ins for the
inputs "Y" in the process "X". This can revolutionize what the process
"X" does since unlike inputs "Y", inputs "Z" might be in a different
modality, nontransient, or able to combine into complex systems
- things that might greatly extend or alter what process "X" can
do.

For example, take process "X" to be the process by which we recognize
spoken words, input "Y" to be the speech sounds - vowels and consonants,
and "Z" to be visual patterns such as A, B or C. These visual patterns
- letters - act as stand-ins for speech sounds, and thus enable
an alternative means by which the word recognition process can identify
words. Speech sounds are transient, and at least before audio recording,
not easily reproduced. Visual patterns, in contrast, can be permanent,
and readily copied even with primitive technologies. Thus, a completely
new cognitive skill could be created upon an old one by the use
of alphabetic symbol stand-ins for speech sounds - reading and writing.
Note, that alphabet letters as stand-ins have a completely arbitrary
linkage with what they take the place of - the letter B has no obvious
link to the sound of the consonant /b/ for which it is a symbol.

Neural plasticity by allowing one thing to stand-in in the brain
for another can profoundly change prior evolved adaptations - in
this case an ability to recognize an image, and the ability to make
or recognize a spoken word, can be combined to create the skills
of reading and writing. An already evolved intelligence - the ability
to recognize words - could through symbols become an artificial
one - literacy - generated afresh in each generation through the
neural programming offered by symbols - writing - from previous
ones.

Symbols are not only important in extending cognitions: they also
enable the novel sociability of the human species - and this played
a critical role in the evolution of our human brain. The two aspects
of sociability that mark out humans from our closest ape relatives
are (1) the existence of communal defined relationships such as
in-laws; and (2) long-term and separation resilient attachments,
particularly those between biological parents. These innovations
were profoundly important since long-term partnerships between parents
enable humans to provide the substantial and reliable resources
needed for child rearing, and in-laws and other socially defined
relationships enable humans to be parts of intricate kinship networks
that further aid this provision through complex forms of group cooperation.
There is a feedback here: these bonds since they increase the resources
for raising children enable the prolonged period of immaturity needed
to develop and then educate brains with extragenetic transmitted
learning.

Such communally defined and long-term robust attachments were
made possible by symbolization. Consider the wedding ring - it is
not merely a piece of metal but a device by which the limbic brain
- the part of the brain responsible for attachments - can keep bonds
robust against the physical separation of individuals by time and
place. Emotional attachment normally requires that brains constantly
affirm their relationship with physical contact and sensory cues
with an attached partner. Without the daily contact that provides
this input into the limbic systems, the emotions of attachment fade.
But a symbol - such as a ring on the finger - can take the place
of these daily contact emotions by standing-in for these limbic
processes for the physical and sensory contact that does not happen.
A wife or husband, for instance, may not see or hear each other
(particularly in the pre-telecommunication age if away at sea or
war) but they are still present to each other through that piece
of metal. Due to neural plasticity, attachment processes in the
limbic system can gain input from this (and other arbitrary stand-ins)
in addition to transient sensory cues provided by the partner's
actual presence. This lets it respond to a new kind of relationship
affirmation: one that is permanent and does not require the presence
of the other partner. That profoundly changes the endurability of
that attachment.

Wedding rings, further, show another aspect of symbols: the limbic
process that once enabled attachment was private between two individuals.
But due to its symbolization such attachment could be made public
and definable by the community. The wedding ring is thus usually
part of a complex symbolic system "marriage" that puts people in
different families into in-law relationships, for example. What
had been personal now could be cultural.

This illustrates how neural plasticity enables completely novel
sociability - one based upon long term and culturally defined bonds.
The circuits in the limbic system did not need to change for this
- what was needed was evolution to give an opportunity for neural
plasticity to allow inputs into the limbic system to be reprogrammed
by symbols.

Here we can see how neuroscience, and evolutionary theory can
together radically change our view of culture. Human evolution did
not select genes to build complex cognitions; it selected them to
make culture that could transmit them. That required human evolution
to specialize the brain to acquire symbols that could rewrite earlier
evolved skills to acquire not only new skills but through them,
new and unnatural - because made by symbols - cultural ways of living.
Such new ways of life, of course, feedback enabling the support
needed for the enlarged human brain.

The revolution of symbols

The brain's discovery that it could extend itself with symbolism
was a revolution. Arguably, it was a watershed as momentous for
the rise of the mind as catalysts were for the rise of life.

First, consider the power of arbitrary links to change what the
brain did. Symbols allow new cognitions. Not only did this vastly
increase processing power, but also it did this without needing
any new evolution of special brain circuits.

But this was only the start of the brain-upgrade story -- symbols
are much more than arbitrary associations. Arbitrary associations
could exist only as a kind of private software that each brain learns
in isolation. But because they are learnt, the human brain could
copy the links discovered and used by other brains. That was a revolution:
brains could select the best from other brains - programming could
itself evolve. That turbocharged what brains could acquire. Again
this would happen without the rest of the brain needing to change.

This even still was only the beginning: brains could combine symbols
into complex information carrying systems, and use such systems
of symbols to organize the rest of the brain -- including the ability
to learn and pass on such learning. Moreover, here was a tool that
it could pick up direct from other brains. The brain catalyst of
symbolism would start catalyzing itself in new directions.

Brains could, for example, with complex symbol systems, go on
to invent worlds that only existed due to them: mathematics, literature
and science. Indeed, one philosopher, Sir Karl Popper, suggested
that they make up a different kind of world: World 3. According
to him, World 3 exists autonomously of the real one in which we
physically live (World 1), and the subjective one of our inner thoughts
(World 2). World 3 is the world of symbols we communicate and store-from
the works of Euclid and of Shakespeare to Google and Internet.

Symbols give us the possibility of mindware - an extragenetic
inheritance that creates our minds upon our brains as software does
upon hardware. Not of a single kind, but of a nearly infinite number
of varieties, limited only by human imagination. Our brains had
contained many ape skills that were ripe to be changed in what they
did. With the right symbolism they could be upgraded to do things
and live forms of life that no other ape could - and with great
diversity.

Here is the importance of neural plasticity. Neural plasticity
argues that our brain is not functionally fixed. Evolution had created
a biocomputer with a wide range of mental skills that were ready,
without further evolution, due to it and the possibilities offered
by symbols, to do totally novel things. Symbols, moreover, gave
brains the ability to be different and pass that difference on.
Neural change could thus undergo, independent of its genes, an evolution
of its own.

Signified and signifiers

These ideas suggest an urgent need for dialogue between anthropologists
and neuroscientists. Cultural anthropologists such as Levi Strauss,
talk of "signifiers" and "signified." What people do with symbols
must involve some underlying processes. Given the brain's role in
making our experience, it would be reasonable to suggest the processing
carried out by neurons. Neurological evolutionary psychology contends,
that when anthropologists talk of signifiers, they are talking of
symbols; and when they talk of the signified, they are in general
talking of the social, attachment and other processing done in the
limbic system.

We can only tentatively sketch rough outlines of how this might
happen. The social life of all people is full of social "don'ts,"
taboos and rituals. One conjecture is that symbol signifiers extended
signified processes in the orbital prefrontal cortex. In apes, they
underlie behavioral "don'ts." Symbolized, they may have made possible
the human experience of morals and etiquette. The experience of
nonwestern and many western people is full of things to fear and
be wary of-magic, pollutants, unlucky numbers, evil eyes, sacred
places, ritual ceremonies and superstitions. Fears and anxieties
are created in the amygdala - might processes in this part of the
brain have become signified through symbols? We wear rings and powder
and paint ourselves. Are processes in the insular or the somatosensory
cortex - which links emotions to our bodies - being signified?

Neurological evolutionary psychology challenges present anthropology
by suggesting that below the symbols of culture hides a brain story.
Social culture, it argues, is the direct result of a skill we did
not realize we had-the ability to symbolize earlier evolved processes
in our brains. We live in cultures -and at the same time mentally
exist due to our brains: they must link. Thus to understand ourselves
requires both the humanities - the nature of these symbols - and
science - the neurology of the original processes that they extend
and modify.

Neurological evolutionary psychology argues that symbolic culture
is a kind of artificial intelligence added on to the natural one
transmitted in our genes. With this artificing of the brain came
a vast leap in what brains could accomplish. With shared symbols,
the human brain retooled its mind to make all manner of new bonds,
new selves, new societies-and indeed-if we include the sacred and
Popper's World 3-new worlds.

This liberated the human brain. No longer was the brain-as it
had been-merely a skull-encased organ programmed with instincts
to survive and reproduce genes. Brains could now go beyond such
needs-symbols freed our brains to experience new things in life.
With mindware humans put themselves apart from other animals and
the rest of nature. Modern people now can see their our brains in
action and soon with technological advances will be able to actively
enhance their development even more than in the past. Neurons with
symbols had started a new journey, one of which is far from finished.